/Engine/Plugins/Experimental/RemoteSession/Source/RemoteSession/Public/Channels/RemoteSessionARSystemChannel.h
Given a pin, remove it and stop updating the associated component based on the tracked geometry. The component in question will continue to track with the world, but will not get updates specific to a TrackedGeometry.
virtual void OnRemovePin ( [UARPin](API\Runtime\AugmentedReality\UARPin) * PinToRemove )